Derivative Financial Instruments - Schedule of Fair Value by Balance Sheet Location (Details) $ in Millions	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Derivative Assets, Fair Value Gross	$ 80.4
Cash collateral	12.5
Derivative Assets, Fair Value, Gross, Net of cash collateral	67.9
Derivative Liabilities, Fair Value, Gross	68.3
Cash collateral	10.9
Derivative Liabilities, Fair Value, Gross, Net of cash collateral	57.4
Foreign exchange contracts	39.0
Foreign exchange contracts	26.9
Derivative Assets, net	26.5
Derivative Liabilities, net	16.0
Over the counter
Derivative [Line Items]
Derivative Assets, Fair Value Gross	80.4
Derivative Liabilities, Fair Value, Gross	68.2
Foreign exchange contracts	39.0
Foreign exchange contracts	26.8
Exchange traded
Derivative [Line Items]
Derivative Assets, Fair Value Gross	0.0
Derivative Liabilities, Fair Value, Gross	0.1
Foreign exchange contracts	0.0
Foreign exchange contracts	$ 0.1

Derivative Asset, Fair Value, Gross, Amount Offset Against Collateral

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Derivative Liability, Fair Value, Gross, Amount Offset Against Collateral

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value, after effects of master netting arrangements, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against the right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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